Applied Mechanics and Materials Vols. 633-634

Abstract: The crack growth behavior in dissimilar weld joints is affected by the mechanical heterogeneity of materials. The subcritical crack growth in dissimilar weld joints was simulated by adopting extended finite element method. The results indicated that the strength mismatch will affected the subcritical crack growth behavior. The growth direction of subcritical crack in material with higher strength will deviate to the interface, and the crack may advance through the interface to material with lower strength if the strength mismatch is critical. The cracks will advance away from the interface if the subcritical crack in soft material.

Abstract: On the basis of traditional hollow blow molding machine head, this paper researches the accumulating corner style machine head. This kind of machine head employs double layers and double spiral flow channels which solve the intensity problem of the large scale blow molding machine with single spiral flow channel on the fusion seam area. His paper researched the technological parameter and structure size based on the structural style.

Abstract: After its addendum modification and tangent modification of involute gear with fewer teeth, its addendum becomes pointed, which results in the bigger difference between the tooth profile of involute gear with fewer teeth and that of the standard. The equation of tooth profile is deduced in condition of pointed addendum of involute gear with fewer teeth and its 3D mathematic model is built. Based on the principle of form milling machining, relative position between the gear and workpiece is found when form machining. Then contact lines of cutter and workpiece are derived and revolution surface and axial section of formed cutter are obtained. Simulating machining is made after the cutter model is built in 3D software. It’s found that the gear obtained by simulating machining coincides fully with that built based on equation of tooth profile, which shows the validity of form milling machining.

Abstract: Accurate prediction and effective control springback has a great significance to the plate cold bending forming. Based on the analysis of the support vector machine method principle and structure, Study on support vector machine prediction process based on MATLAB and prediction models about radius and resilience is set up. And the results predicted were compared with BP neural network prediction results to verify the accuracy.To provide an effective method for the accurate prediction springback.

Abstract: Obtaining narrower kerf and smaller heat affected zone (HAZ) is a difficulty in laser cutting carbon fiber reinforced plastic (CFRP) composites. In order to solve this problem, the experiments used a semiconductor UV laser to cut CFRP have been done and how laser parameters (include pulse power, repetition frequency, cutting speed and direction) influent the width and HAZ of kerf have been achieved. In the meantime, compared with infrared laser cutting CFRP, the quality of CFRP cut by different wavelength laser has been investigated. The results show that owing to CFRP has the characteristic of anisotropy, laser cutting direction is the most significant factor that affects the quality of kerf cut by UV laser. The study also found that owing to high single photon energy, the narrower kerf and smaller HAZ around kerf can be get by UV laser cutting CFRP, nevertheless, it can’t be achieved by infrared laser cutting CFRP.

Abstract: TC21 is a first high strength and damage-tolerant titanium alloy self-developed in China, which has independent intellectual property. As it is known to all, titanium alloy TC21 is one of the most widely used materials in aerospace. The improvement of cutting quality of titanium alloy is an urgent problem. In this paper, the orthogonal experiment were carried out to study surface roughness of turning TC21. The predictive model of surface roughness in turning TC21 was built by analysis of multivariable linear regression on the basis of experiment. Statistical test results indicated the established predictive model were in highly notable test status and had high reliability. These works provide references for machining TC21.

Abstract: Compression molding is the most important method to gain high quality bonded NdFeB magnets. The production process is preparation of composite powder, compression molding, coating and magnetizing. Based on test and lot production practice, the important effects of compression molding actions, mould structure and mould material on magnet quality are analyzed. The mold structures for ring-magnet and arc-magnet are fixed. The key techniques that controlling the quality of bonded NdFeB magnets are summarized.

Abstract: The effect on the stability of the analysis of time lag effect of the milling system，Reveals the root cause of the milling type regenerative chatter occurs，Milling type regenerative chatter is derived from the time-delay feedback within the system，Application of routh criterion and Fourier analysis of chatter in milling system before and after the change of rigidity and damping system, it is concluded that the limit cutting depth.

Abstract: To design a set of force-applying mechanism, simulate the stresses of workbench in vertical milling process and complete dynamic test of performance parameters by controlling the mechanism on the basis of the research of a testing stand of precision preserve of rolling functional components. This paper establishes a mechanical model to simulate the milling stresses of workbench, and makes use of the principle of the force and moment equal to deduce the functional relationships between the force of mechanism applying and the milling force, makes appropriate transformation according to the working principle of force-applying mechanism; adopt the “PC+NC” NC system architecture and use VB complete programming of the testing stand open NC system based on the multiple axis controller PMAC. Operators can achieve the function of testing stand by the established system interface. In the process of the test of performance parameters by testing stand, the force-applying mechanism applies milling force which could ensure test data accuracy and also save energy.

Abstract: This work aims at brazing 70 vol.% SiCp/Al composites using Al-15Cu-8.5Si-4Ni-1.5Mg alloy powder as filler metal. The microstructures and shear strengths of the joints made with 70 vol. % SiCp/Al composites at different brazing temperature and different holding time were examined. It is found that the brazing temperature has an apparent effect on the quality of the joints. The sample brazed at 580 °C, with the holding time of 90 min demonstrates the best metallurgical bonding. The joint mainly contains α-phase, flake-like eutectic silicon, small amounts of primary silicon and bright white θ (Al₂Cu) phase. The maximum shear strength of the brazed joint is 49.7MPa, and the fracture surface shows the characteristic of brittle fracture.